Interpretation

Small increases in catecholamines (less than 2 times the upper reference limit) usually are the result of physiological stimuli, drugs, or improper specimen collection.  Significant elevation of one or more catecholamines (2 or more times the upper reference limit) is associated with an increased
probability of a neuroendocrine tumor. Measurement of plasma or urine fractionated metanephrines provides better diagnostic sensitivity than measurement of catecholamines.  

Higher catecholamine concentrations are observed in specimens collected from upright or standing adults.  Epinephrine may be increased by approximately 20 percent; norepinephrine up to 700 pg/mL; dopamine, unchanged.

NOTE: Medications that may interfere with catecholamines and metabolites include amphetamines and amphetamine-like compounds, appetite suppressants, bromocriptine, buspirone, caffeine, carbidopa-levodopa (Sinemet), clonidine, dexamethasone, diuretics (in doses sufficient to deplete sodium), ethanol, isoproterenol, labetalol, methyldopa (Aldomet), MAO inhibitors, nicotine, nose drops, propafenone (Rythmol), reserpine, theophylline, tricyclic antidepressants, and vasodilators. The effect of drugs on catecholamine results may not be predictable. 

For optimum results, patient should be supine for 30 minutes prior to collection.
Children, particularly those under 2 years of age, often show an elevated catecholamine response to stress.